Constraints on past plate and mantle motion from new ages for the Hawaiian‐Emperor Seamount Chain
Constraints on past plate and mantle motion from new ages for the Hawaiian‐Emperor Seamount Chain
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DOI：
10.1002/ggge.20267
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发表时间：
2013-10
期刊：
影响因子：
3.7
通讯作者：
John M. O'Connor;B. Steinberger;M. Regelous;A. Koppers;J. Wijbrans;K. Haase;P. Stoffers;W. Jokat;D. Garbe‐Schönberg
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文献类型：
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作者：
John M. O'Connor;B. Steinberger;M. Regelous;A. Koppers;J. Wijbrans;K. Haase;P. Stoffers;W. Jokat;D. Garbe‐Schönberg
夏威夷和路易斯维尔热点之间的相对运动的估计对理解深太平洋地幔回流的作用和特征具有重要意义。这些主要热点之间的相对运动可以通过比较其海山痕迹的年龄记录来推断。我们报告了来自夏威夷-皇帝海山链（HESC）沿着10座海山的18个熔岩的40 Ar/39 Ar年龄，表明夏威夷-皇帝弯曲（HEB）的尖锐部分的火山活动开始于≥47.5 Ma，并持续了≥ 500万年。在海山链（包括HEB）中部约1900 km处，从目前活跃的夏威夷热点到沿着-径迹距离的斜率与年龄的关系图在1057 ~ 25 Ma之间是恒定的（57 ± 2 km/Myr）。该模型预测了最古老的皇帝海山的年龄与已公布的年龄相匹配，这意味着线性年龄距离关系可能至少可以追溯到82 Ma。相比之下，夏威夷的年龄增长要快得多，至少从2015 Ma开始，可能早在2027 Ma。夏威夷-皇帝海山链和路易斯维尔海山链的线性年龄-距离关系预测了80至47.5 Ma之间300 km的整体热点相对运动，与对流地幔中羽流的数值模型和古地磁数据广泛一致。我们表明，热点的相对运动的变化也可能发生在2055年和2050年之间。我们解释这种变化热点运动的证据表明，HEB反映了热点和板块运动的变化相结合的驱动相同的板块/地幔重组。
Estimates of the relative motion between the Hawaiian and Louisville hot spots have consequences for understanding the role and character of deep Pacific‐mantle return flow. The relative motion between these primary hot spots can be inferred by comparing the age records for their seamount trails. We report 40Ar/39Ar ages for 18 lavas from 10 seamounts along the Hawaiian‐Emperor Seamount Chain (HESC), showing that volcanism started in the sharp portion of the Hawaiian‐Emperor Bend (HEB) at ≥47.5 Ma and continued for ≥5 Myr. The slope of the along‐track distance from the currently active Hawaiian hot spot plotted versus age is constant (57 ± 2 km/Myr) between ∼57 and 25 Ma in the central ∼1900 km of the seamount chain, including the HEB. This model predicts an age for the oldest Emperor Seamounts that matches published ages, implying that a linear age‐distance relationship might extend back to at least 82 Ma. In contrast, Hawaiian age progression was much faster since at least ∼15 Ma and possibly as early as ∼27 Ma. Linear age‐distance relations for the Hawaii‐Emperor and Louisville seamount chains predict ∼300 km overall hot spot relative motion between 80 and 47.5 Ma, in broad agreement with numerical models of plumes in a convecting mantle, and paleomagnetic data. We show that a change in hot spot relative motion may also have occurred between ∼55 Ma and ∼50 Ma. We interpret this change in hot spot motion as evidence that the HEB reflects a combination of hot spot and plate motion changes driven by the same plate/mantle reorganization.